To publicize the fact that these sort of attacks can be tracked. Similar to when they publish information about particularly crafty drug houses they bust: so that people planning on building a drug house think "well, if they got that house, then they'll definitely find out the one I'm planning, so maybe I'd better not."
Potentially the purpose is that if someone goes to the effort to get those details together, they are more likely to send the same report to other trusted individuals. Maybe it was originally there to add legitimacy, then they got a report sent in, and removed it to slow the spread of awareness
I expect the idea is less to prevent any possible threat and is more a) to comply with regulations and b) to log enough data so if somebody does circumvent your legally required measures, they've left enough of a trail to hang themselves.
For example when CIA/NSA tools leaked, one of them had precisely this purpose.
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